/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.edu.thu.laud.objectstore.fieldmanager;

import org.datanucleus.ObjectManager;

import cn.edu.thu.laud.objectstore.index.BatchMutation;

/**
 * @author zhuoan 
 *
 */
public abstract class ObjectManagerMutate {
	
	protected ObjectManager om;
	protected BatchMutation mutator;
	private int count;

	public ObjectManagerMutate(ObjectManager om, BatchMutation mutator) {
		this.om = om;
		this.count = 0;
		this.mutator = mutator;
	}

	/**
	 * Get the execution context this mutate belongs to
	 * 
	 * @return
	 */
	public ObjectManager getObjectManager() {
		return om;
	}
	/**
	 * Push the current on to our stack for this execution context
	 * 
	 * @param instance
	 */
	public void pushInstance() {
		count++;
	}

	/**
	 * Pop the current instance from our execution context
	 * 
	 * @param instnace
	 * @return
	 */
	public boolean popInstance() {
		count--;
		return count == 0;

	}
	
	/**
	 * @return the mutator
	 */
	public BatchMutation getMutator() {
		return mutator;
	}
	
	public abstract void execute() throws Exception;
	
	
}
